Natural and Unnatural Disasters

A few years ago I made a pilgrimage to Pumping Station No. 6, which
sits athwart the 17th Street canal in New Orleans. Approaching from
the intake side, I found a brick building whose entire facade was
hidden behind an immense "trash rack," a grille of steel
bars that intercept floating debris. Inside, bulbous steel casings
enclosed pumps 12 feet in diameter, driven by equally large electric
motors. Much of this machinery was installed in 1915 and has a
certain antique splendor about it, but the pumps are not museum
pieces; they are still among the most powerful in the world. It is
these pumps, along with a network of drainage canals and a ring of
protective levees, that made it possible to build a sprawling city
in the cypress swamps between the Mississippi River and Lake
Pontchartrain, where half a million people have been living
"below ground zero," as one fleeing resident recently
described the place.

The pumps are just a small part of the engineered infrastructure
that underpins the existence of New Orleans and its suburbs. The
entire lower reach of the Mississippi River runs through an
artificially stabilized channel. The banks are armored with stone
and concrete and surmounted with levees and floodwalls. In some
places the course of the river has been straightened; almost
everywhere the channel has been dredged. A few miles upriver from
New Orleans, the Bonnet Carré Spillway drains flood waters
into Lake Pontchartrain. Farther upstream, even bigger spillways at
Morganza and Old River divert seasonal overflows into the
Atchafalaya River, which empties into the Gulf of Mexico at Morgan
City, 50 miles west of New Orleans.

All of this hydraulic engineering has been remarkably successful, at
least in the narrow sense that floods on the lower Mississippi have
been contained and controlled. New Orleans has not had river water
in its streets for more than a century. But the river is not the
only threat to the city—and this was already well known even
before Hurricane Katrina made it painfully clear at the end of August.